Numerous types of pathogens, in particular fungi, infect turfgrass plants on golf course greens causing a loss of revenue from reduced playability. Agricultural active chemicals for controlling pathogens, such as fungicides and insecticides, are typically applied as needed depending on extent of disease pressure, pathogen population, weather, and the like. However application is highly controlled by course budget, availability of appropriate equipment, and availability of qualified personnel for applying agricultural active chemicals.
One example of a common problem for golf course managers is a dollar spot infection caused by a fungal pathogen (Sclerotinia homoeocarpa) on many turf grass plants found on golf courses, including Kentucky bluegrass, perennial ryegrass, buffalo grass, bermudagrass, bentgrass, and zoysiagrass plants. Dollar spot blights leaf tissues but typically does not affect turfgrass roots or crowns, resulting in the formation of small, roughly circular, brown patches in grass growing areas. Most spots are merely a few inches in diameter. However, under favorable environmental conditions, individual spots may exceed 6 inches in diameter. Affected plants within the diseased spots wilt, eventually turning tan or brown. During outbreaks of the disease, numerous spots on the turfgrass coalesce into large irregular dead areas. Several types of approaches are used to control dollar spot infections, including individual applications of nonchemical, biological and chemical compositions.
Nonchemical control is attempted by a balanced nitrogen fertility program in which adequate nitrogen nutrition is believed to result in plants that are less prone to disease. Another method of nonchemical control is to cultivate resistant varieties of turf grass, such as a L-93 cultivar of bentgrass. Further, irrigation scheduling may contribute to dollar spot control since the duration of the dew period is proportional to the extent of infection. As such, any irrigation practice that lessens the dew period may contribute to less serious disease outbreaks. Biological control of dollar spot is attempted by fertilization with composted turkey litter, bovine wastes, organic amendments and compositions comprising Bacillus licheniformis. Chemicals considered active ingredients used for dollar spot control include chlorothalonil, fenarimol, iprodione, thiophanate-methyl, etc.
However, in addition to being highly labor intensive, the effectiveness of these individual applications is variable, requiring multiple applications for each purpose Such applications are also expensive, requiring dedicated equipment for each type of application.
Thus, there exists a need for improved methods of pathogen control on cultivated turf grass that ideally are economically feasible for management programs.